1. Field of the Invention
This invention relates generally to solar dish concentrators that focus solar radiant energy upon a collector and more particularly to an ellipsoidal concentrator that projects an uniform radiant flux onto an annulus shaped receiver body.
2. Description of the Prior Art
Solar energy collecting apparatus is well-known in the art. Traditional solar collectors utilize a reflector which focuses solar energy upon heat exchanging apparatuses. The reflector may be a parabolic, elliptical, or a circular cylindrical type mirror. The efficiency of the traditional solar collector is determined by the percentage of incident solar radiation that can be focused on the heat exchanging apparatus. The heat exchanging apparatus normally consists of tubes located at the focus point of the solar collector which carry a heat conducting fluid.
The principal object of prior art solar collectors is to focus a maximum amount of solar radiation to a single focus point where the heat exchanging apparatus is located. To accomplish this, various collector shapes have been utilized and in addition sun tracking systems have been used to control the angle of incident solar radiation to maximize the efficiency of the system.
New receiver-solar engine combinations based on the Sterling Engine Principle have been developed that require a uniform flux density having a peculiar shape of the concentrated solar flux pattern which can best be described as a concave annulus. These new receivers require that the solar radiation be evenly distributed over the four quadrants of the receiver without any hot spots. The traditional concentrators cannot meet these demands. A variety of paraboloidal and spheroidal concentrators have been developed, but none have been completely successful at creating the proper flux pattern. It would be desirable if a solar dish concentrator were provided that focused a uniform flux density on a receiver.